In a seat air conditioning unit for a vehicle disclosed in U.S. Pat. No. 5,934,748, a seat cushion and a backrest of a seat have air passages, heating coil and blower units, respectively. The heating coil and the blower unit are controlled based on temperature determined by a temperature sensor provided at a predetermined position in the seat, thereby optimizing a condition of air in the seat.
Generally, the seat cushion receives pressure from a seat user larger than that the backrest receives. With this, the seat cushion bends larger than the backrest, resulting in an increase in an air flow resistance of the air passage in the seat cushion. In the above seat air conditioning unit, however, the blower units are provided without consideration of difference between air flow resistances of the seat bottom and the backrest.